The most abundant pure organic chemical in the world is sucrose. See Kirk-Othmer, Encyclopedia of Chemical Technology, 3d Edition, Volume 21, John Wiley & Sons, New York, pages 921-948 (1983). However, although sucrose produced from sugar cane and sugar beets is ubiquitous in its availability and is of relatively low cost, only a fraction of a percent by weight is consumed as a chemical feedstock. The potential value of sucrose as a raw material has been recognized for many years and has been the subject of considerable research.
Sucrose is a particularly appropriate material for use in the formation of esterified products produced currently from petroleum-based materials because (a) it is a naturally occurring, relatively abundant renewable material; (b) it is polyfunctional with three reactive primary alcohols that can readily be derivatized; (c) it is a nonreducing sugar and thus does not have the potential for the wide variety of side-reactions that reducing sugars have; (d) it has a relatively easily hydrolyzed glycosidic linkage that allow sucrose polymers to be potentially more biodegradable than polymers made with other carbohydrates, such as sugar alcohols; and (e) it is a naturally occurring sweet carbohydrate in common use and therefore potentially useful in the formation of potential non-absorbable, noncaloric sweeteners.
The usual technique for the synthesis of carbohydrate esters involves a reaction of the carbohydrate with an acid chloride or acid anhydride in a basic organic solvent, such as triethylamine, pyridine or quinoline. In a few instances, the organic base has been replaced by sodium hydroxide. However, the prior art teaches very little about the reaction of sucrose with polyfunctional reagents.
Although relatively few successful derivatives of sucrose have been commercialized, there has been substantial interest in developing sugar-based synthetic technology. Thus, in 1953, Sonntag, in Chemical Reviews52 at page 321, described a technique where a polyhydroxy compound was dissolved in a large excess of a tertiary amine, and by adding thereto an acid chloride, preferably in a solvent such as chloroform. However, only mixtures in low yields were obtained which were not easy to separate.
On the other hand, the preparation of pure regiospecific esters of polyhydric alcohols (carbohydrates) is a more complicated problem requiring special innovation, such as prior to reaction, the blocking of certain hydroxyl groups in the polyalcohol with easily removable groups.
In the patented literature, U.S. Pat. No. 2,927,919 relates to ether-esters of sucrose, U.S. Pat. No. 3,170,915 discloses sucrose ethers and U.S. Pat. No. 3,300,474 discloses the preparation of sucrose ether co-polymerizates.